Age and growth of the squid Sepioteuthis lessoniana in N.W. Luzon, Philippines

Abstract

The statoliths of 33 Sepioteuthis lessoniana from Bolinao, north-western Luzon, Philippines, were examined microscopically for growth increments. The daily nature of the increments was verified for captive specimens (<6 cm) kept in a tank containing Alizarin solution and fed with shrimps previously soaked in Alizarin solution. The ages ranged from 30-40 days in juveniles (19-33 mm dorsal mantle length DML) to 62-132 days in adults (62-315 mm DML). The growth rates estimated (0.5 mm.day-1 in adults) were much higher than those estimated by length-frequency analysis, but compatible with published estimates based on the statoliths of specimens sampled in Australia and Japan. The discrepancy between the results of length-frequency analysis and statolith ageing is attributed, at least in part, to underestimation of the age of older squid.